Breast pump



FIG. 1 is a rear elevational view of a breast pump, showing our new design;

FIG. 2 is a side perspective view thereof;

FIG. 3 is a front elevational view thereof; and,

FIG. 4 is another side perspective view thereof.

The broken line showing in FIGS. 1, 2 and 4 is for illustrative purposes only and forms no part of the claimed design. 

The ornamental design for a breast pump, as shown and described. 